GRB 220308A
GCN Circular 31715
Subject
IPN triangulation of GRB 220308A (long / very bright)
Date
2022-03-08T22:36:37Z (3 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,
E. Bozzo, and C. Ferrigno,
on behalf of the INTEGRAL SPI-ACS GRB team,
and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:
The very bright, long-duration GRB 220308A
has been detected by Konus-Wind, INTEGRAL (SPI-ACS),
Fermi (GBM), Swift (BAT), and AGILE (MCAL),
so far, at about 20588 s UT (05:43:08).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
356.500 (23h 46m 00s) +23.844 (+23d 50' 40")
Corners:
358.094 (23h 52m 23s) +22.701 (+22d 42' 02")
355.336 (23h 41m 21s) +25.088 (+25d 05' 19")
354.810 (23h 39m 15s) +24.953 (+24d 57' 11")
357.591 (23h 50m 22s) +22.579 (+22d 34' 45")
---------------------------------------------
The error box area is 1.44 sq. deg, and its maximum
dimension is 3.75 deg (the minimum one is 25 arcmin).
The Sun distance was 30 deg.
This box may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB220308_T20585/IPN/
The time history and spectrum will be given in forthcoming
GCN Circulars.
GCN Circular 31716
Subject
GRB 220308A: Swift/BAT-GUANO detection outside the coded FOV
Date
2022-03-09T02:30:44Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220308A onboard (T0: 2022-03-08T05:43:08
UTC, INTEGRAL/SPI-ACS trig#9761, IPN GCN 31715).
The INTEGRAL notice, distributed in near real-time, triggered the
Swift Mission Operations Center operated Gamma-ray Urgent Archiver for
Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst
Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from
[-45,+45] seconds around the time of the burst. All the requested
event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu,
arXiv:2111.01769), detects the burst with a sqrt(TS) of 97 in a 8.192
s analysis time bin.
The duration of this burst episode is ~10s.
NITRATES results indicate a burst coming from outside the coded FOV,
with DeltaLLHOut of -240. An out of FOV origin is consistent with the
IPN timing localization (GCN 31715).
See Section 9.1 and Figure 20 in the NITRATES paper for brief
descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
GCN Circular 31719
Subject
CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
Date
2022-03-09T09:01:19Z (3 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
P. S. Marrocchesi (U of Siena),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
and the CALET collaboration:
At 05:35:27.809 UTC on 8 March 2022, the CALET Gamma-ray Burst Monitor
(CGBM) triggered on a long weak GRB followed in ~460 s by the bright
GRB 220308A, localized by the IPN (Svinkin et al., GCN 31715;
https://gcn.gsfc.nasa.gov/other/220308A.gcn3).
Both bursts were seen by all CGBM detectors.
The first (trigger) burst might be a precursor of GRB 220308A.
The trigger burst light curve shows a double-peaked pulse which starts at
T+1.9 sec, peaks at T+3.6 sec,and ends at T+15.0 sec. The T90 and T50
durations measured by the SGM data are 11.6 +- 1.6 sec and 7.4 +- 1.6 sec
(40-1000 keV), respectively.
The GRB 220308A light curve shows a multi-peaked structure which starts
at T+461.6 sec, peaks at T+465.9 sec, and ends at T+481.9 sec.
The T90 and T50 durations measured by the SGM data are 15.4 +- 0.4 sec
and 4.0 +- 0.1 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1330752907/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 31723
Subject
Konus-Wind detection of GRB 220308A
Date
2022-03-09T22:19:58Z (3 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova,
A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 220308A
(IPN triangulation: Svinkin et al., GCN Circ. 31715;
Swift/BAT-GUANO detection: Tohuvavohu et al., GCN Circ. 31716;
CALET-CGBM detection: Marrocchesi et al., GCN Circ. 31719)
triggered Konus-Wind at T0=20585.134 s UT (05:43:05.134).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.1 s and has a total duration of ~69 s.
The emission is seen up to ~15 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220308_T20585/
As observed by Konus-Wind, the burst
had a fluence of 2.87(-0.11,+0.11)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+1.296 s,
of 1.06(-0.10,+0.10)x10^-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+22.016 s)
is best fit in the 20 keV - 16 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.93(-0.02,+0.02),
the high energy photon index beta = -3.42(-6.58,+0.47),
the peak energy Ep = 1099(-55,+57) keV
(chi2 = 130/97 dof).
The spectrum near the maximum count rate
(measured from T0+1.024 to T0+1.536 s)
is best fit in the 20 keV - 16 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.26(-0.09,+0.10),
the high energy photon index beta = -3.13(-1.01,+0.41),
the peak energy Ep = 1419(-150,+155) keV
(chi2 = 69/66 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 31733
Subject
GRB 220308A: AGILE detection
Date
2022-03-10T14:05:01Z (3 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
A. Ursi (INAF/IAPS), A. Di Piano (INAF/OAS-Bologna), F. Verrecchia, C.
Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor
Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, E. Menegoni,
L. Foffano, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and INAF/OAR), A.
Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M.
Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois
(INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN
Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
The AGILE satellite detected the long GRB 220308A at T0 = 2022-03-08
05:43:08 (UTC), reported by INTEGRAL/SPI-ACS (trig#9761), Fermi/GBM
(trigger no.668410535), CALET (GCN #31719), Konus-Wind (GCN #31723),
Swift/BAT (GCN #31716), and triangulated by IPN (GCN #31715).
The burst is clearly visible in the AGILE scientific ratemeters of the
SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about 22 s and
it released a total number of 2675 counts in the SA detector (above a
background rate of 140 Hz), 54840 counts in the MCAL detector (above a
background rate of 1300 Hz), and 104080 counts in the AC detector (above a
background rate of 3680 Hz). The AGILE ratemeter light curves can be found
at https://tools.ssdc.asi.it/ImgView/Agile/GRB220308A_AGILE_RM29 .
The event also triggered a partial high time resolution MCAL data
acquisition, covering the main peaks of the burst, from T1 = 2022-03-08
05:43:08.21 s +/- 0.01 (UTC) to T2 = 2022-03-08 05:43:15.06 +/- 0.01 s
(UTC), and released 16490 counts in the detector, above a background rate
of 640 Hz. The time-integrated spectrum of the burst in this time interval
can be fitted in the energy range 0.4-10 MeV with a Band function with
alpha = -0.70 (frozen), beta = -2.45 (-0.11/+0.09), and Epeak = 760
(-98/+97) keV, resulting in a reduced chi-squared of 1.32 (47 d.o.f.) and a
fluence of 1.4e-04 ergs/cm^2 (90% confidence level), in the same energy
range. The MCAL light curve can be found at:
https://tools.ssdc.asi.it/ImgView/Agile/077313_GRB_57380300810779330 .
Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert
Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html. Please
note that in the MCAL notice #573803008 the T0 was affected by a temporal
shift of about +19.5 sec due to episodic automated ground software problems
which are then corrected offline.
GCN Circular 31734
Subject
Fermi GBM Detection of GRB 220308A
Date
2022-03-10T20:42:33Z (3 years ago)
From
Cori Fletcher at USRA <cfletcher@usra.edu>
C. Fletcher (USRA), O. J. Roberts (USRA) and J. Wood (NASA/MSFC) report on behalf of the Fermi-GBM Team:
Swift/BAT-GUANO detected GRB 220308A at 05:43:08 UT (GCN 31716), which was also detected by INTEGRAL/SPI-ACS (trig#9761), IPN (GCN 31715), Konus-Wind (GCN 31723), CGBM (GCN 31719), and AGILE (GCN 31733).
The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals identified a transient most significantly on the 2.048 s consistent with GRB 220308A. The GBM targeted search location is RA=350.6, DEC = 4.7 (J2000 degrees, equivalent to 23 h 22 m, 04 d 42'), with an approximate 68% error radius of 10.6 degrees (statistical plus a core-plus-tail systematic model, with 77% of GRBs having a 2.4 deg error and the remaining fraction having a 10.9 deg error.)
The time-averaged spectrum (using a T0 of 2022-03-08T05:43:00 UT) from T0+8.000 s to T0+28.480 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.0 +/- 0.0 and the cutoff energy, parameterized as Epeak = 1371 +/- 26 keV. The event fluence (10-1000 keV) in this time interval is (1.53 +/- 0.05)E-04 erg/cm^2.
There was a Fermi-GBM onboard trigger of a gamma-ray burst (GRB 220308B, GCN 31726) approximately 460 s before GRB 220308A, however, we do not believe these two events to be related.
The spectral analysis results presented above are preliminary.
[1] Goldstein et al. 2019 arXiv:1903.12597